This invention relates to a method of and a device for detection of knocking for an internal combustion engine. In an internal combustion engine, in order to prevent the power-loss and the increased fuel comsumption and noise due to an abnormal combustion of the fuel inside the combustion chamber, it is customary to detect the generation of knocking and adjust atomatically the ignition timing or the fuel-injection timing of a spark-plug ignition engine or the fuel-injection timing of a compression ignition engine to just before the generation of knocking or to the state of very low knocking; that is to adjust the ignition timing automatically to the ideal timing. And, in the past, in detecting the generation of knocking, a resonance type vibrometer which was usually called a knock sensor was attached on a cylinder block to detect the vibration inside the cylinder block generated by the knocking inside the combustion chamber of the cylinder block. However, there are many other sources of vibration from knocking on an engine block which comprises of a cylinder block and a cylinder head which are connected to each other such as cams, valves, bearings, and others. The vibration generated by knocking which is called the signal and the vibration generated by other which is called the noise are mixed together, and the knock sensor not only detects the signal, S, but also the noise, N, as well, and a high value of SN ratio can not be obtained. In order to increase the SN ratio, it is necessary to design the engine block to have a natural frequency which is quite different from the frequency of knocking. However, it is extremely difficult to establish a natural frequency accurately because it is difficult to obtain very accurate finish dimensions such as the wall thickness since block is usually made out of iron casting or aluminum casting. Therefore, in the previous methods of knocking detection, the ratio of SN was low, the accuracy of knocking detection was low, and it was difficult to control the ignition timing or the fuel-injection timing accurately.